System and method for the effective and reliable delivery of controlled amounts of a medical fluid

ABSTRACT

A method for using CO 2  as a contrast material in medical imaging procedures is disclosed. The method includes providing a source of pressurized CO 2 . The step of providing includes connecting the source of pressurized CO2 to a compressed gas unit for controlling delivery of the CO 2 . The method also includes regulating pressure of the CO 2  delivered by the compressed gas unit, transmitting the pressurized CO 2  from the compressed gas unit to a control valve assembly for delivery to a patient in controlled dosages, and sequentially processing the CO 2  with the control valve assembly and delivering the CO 2  to the patient as a contrast media.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Patent Application Ser. No. 14/497,691, filed Sep 26, 2014, entitled “System and Method for the Effective, Reliable and Foolproof Delivery of Controlled Amounts of a Medical Fluid”, which is currently pending, which is a continuation in part of U.S. Patent Application Ser. No. 13/857,448, filed Apr 5, 2013, entitled “Portable Medical Gas Delivery System”, which is now U.S. Pat. No. 9,486,594, which is a continuation in part of U.S. Patent Application Ser. No. 13/068,680, filed May 17, 2011, entitled “Apparatus and Process for Producing CO2 Enriched Medical Foam”, which is now U.S. Pat. No. 8,876,749, which is a continuation in part of U.S. Patent Application Ser. No. 12/652,845, filed Jan. 6, 2010, entitled “Portable Medical Gas Delivery System”, which is abandoned, which is a continuation in part of U.S. Patent Application Ser. No. 12/210,368, filed Sep. 15, 2008, entitled “Portable Medical Foam Apparatus”, which is abandoned, which is a continuation in part of U.S. Patent Application Ser. No. 11/945,674, filed Nov. 27, 2007, entitled “Portable Evaporative Snow Apparatus”, now U.S. Pat. No. 7,543,760, which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/867,323, filed Nov. 27, 2006, entitled “Portable Evaporative Snow Apparatus”, which is expired, and this application is a continuation of U.S. Patent Application Ser. No. 14/497,691, filed September 26, 2014, entitled “System and Method for the Effective Reliable and Foolproof Delivery of Controlled Amounts of a Medical Fluid”, which is currently pending, which is a continuation in part of U.S. Patent Application Ser. No. 13/065,621, filed March 25, 2011, entitled “System for Controlled Delivery of Medical Fluids”, which is now U.S. Pat. No. 9,050,401, which claims the benefit of U.S. Provisional Patent Application Ser. No. 61/395,892, filed May 19, 2010, entitled “System for Controlled Delivery of Medical Fluids”, which is expired, the disclosures of which are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a portable system for safely and efficiently producing and delivering CO₂ and other gases for use in medical applications.

2. Description of the Related Art

Conventional devices for delivering gas such as carbon dioxide (CO₂) for use in medical procedures typically utilize large storage tanks and regulators. Such devices are dangerous because of the risk of a seal, valve or part malfunction, which can produce a projectile in a medical setting. In addition, existing tank systems are quite expensive, extremely cumbersome and usually impractical to transport to off-site locations. These systems typically require a considerable amount of storage space. Current tanks also require filling at a filling station, which can involve the transport of a large quantity of gas such as CO₂. Pressurized gas tanks can explode in the event of a motor vehicle crash. Re-fillable tanks can also exhibit rust, bacteria and contamination, which are not acceptable in a medical environment.

Still further, various types of medical equipment have been utilized to deliver controlled volumes of liquid and gaseous substances to patients. One field that involves the administration of such fluids is radiology, wherein a small amount of carbon dioxide gas or an alternative contrast media may be delivered to the vascular system of the patient to displace the patient's blood and obtain improved images of the vascular system. Traditionally, this has required that the CO₂, or other media first be delivered from a pressurized cylinder to a syringe. The filled syringe is then disconnected from the cylinder and reconnected to a catheter attached to the patient. If additional CO₂ is needed, the syringe must be disconnected from the catheter and reattached to the cylinder for refilling. Not only is this procedure tedious and time consuming, it presents a serious risk of introducing air into the CO₂ or contrast fluid at each point of disconnection. Injecting such air into the patient's blood vessels can be extremely dangerous and even fatal.

Recinella et al., U.S. Pat. No. 6,315,762 discloses a closed delivery system wherein a bag containing up to 2,000 ml of carbon dioxide or other contrast media is selectively interconnected by a stopcock to either the chamber of a syringe or a catheter attached to the patient. Although this system does reduce the introduction of air into the administered fluid caused by disconnecting and reconnecting the individual components, it still exhibits a number of shortcomings. For one thing, potentially dangerous volumes of air are apt to be trapped within the bag. This usually requires the bag to be manipulated and flushed multiple times before it is attached to the stopcock and ultimately to the catheter. Moreover, this delivery system does not feature an optimally safe and reliable, foolproof operation. If the stopcock valve is incorrectly operated to inadvertently connect the carbon dioxide filled bag or other source of carbon dioxide directly to the patient catheter, a dangerous and potentially lethal volume of CO₂ may be delivered suddenly to the patient's vascular system. It is medically critical to avoid such CO₂ flooding of the blood vessels.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a system for safely and reliably delivering a controlled dosage of a fluid to a medical patient.

It is a further object of this invention to provide a fluid (i.e. liquid or gas) delivery system that is particularly effective for use in administering CO₂, or other contrast media in a controlled manner to a patient's vascular system to provide improved contrast for radiological imaging.

It is a further object of this invention to provide a fluid delivery system and particularly a CO₂, contrast media delivery system that prevents potentially dangerous amounts of air from entering the fluid and thereby being administered to the patient.

It is a further object of this invention to provide a fluid delivery system that prevents accidentally flooding of the patient's vascular system with carbon dioxide or other administered gases or liquids under positive pressure.

It is a further object of this invention to provide a fluid delivery system exhibiting a failsafe and foolproof operation, which permits only reliable and accurately controlled dosages of a medical fluid to be administered to a patient.

It is a further object of this invention to provide a fluid delivery system that may be used safely and effectively with virtually any source of carbon dioxide or other medical fluid regardless of the pressure or environment under which that fluid is maintained.

It is a further object of this invention to provide a fluid flow system that prevents an administered medical fluid from flowing in an unintended direction through the system.

In accordance with these objects, the present invention provides a method for using carbon dioxide as a contrast material in medical imaging procedures. The method includes providing a source of pressurized carbon dioxide, connecting the source of pressurized carbon dioxide to a compressed gas unit including a solenoid for controlling delivery of the carbon dioxide, regulating pressure of the carbon dioxide delivered by the compressed gas unit and transmitting the pressurized carbon dioxide from the compressed gas unit to a control valve assembly for delivery to a patient in controlled dosages. Thereafter, the carbon dioxide is sequentially processed with the control valve assembly and delivered to the patient as a contrast media.

It is also an object of the present invention to provide a method wherein the step of sequentially processing includes delivering carbon dioxide through a series of syringes such that it is impossible to directly connect the compressed gas unit to the patient.

It is also an object of the present invention to provide a method wherein the step of sequentially processing includes providing inlet and outlet conduits connected respectively to the compressed gas unit and the patient. The method also includes providing first and second syringes and the control valve assembly, which are interconnected between the inlet and outlet conduits.

It is also an object of the present invention to provide a method wherein the control valve assembly includes a valve body having aligned inlet and outlet ports that are respectively communicably connectable to the inlet conduit and the outlet conduits. The valve body further includes a first intermediate port to which the first syringe is selectively connected and a second intermediate port to which the second syringe is selectively connected. The control valve assembly further includes a stopcock element mounted rotatably within the body and including a channel consisting essentially of a first channel segment and a second channel segment. The first channel segment and the second channel segment are selectively alignable with the inlet port and the first intermediate port to allow for communication between the inlet conduit and the first syringe. The first intermediate port and the second intermediate port allow for communication between the first syringe and the second syringe, and the second intermediate port and the outlet port to allow for communication between the second syringe and the outlet conduit.

It is also an object of the present invention to provide a method wherein the step of sequentially processing includes operating the control valve assembly to communicably join the compressed gas unit and the first syringe and transmitting carbon dioxide from the compressed gas unit to only the first syringe, adjusting the control valve assembly to communicably join the first and second syringes while isolating the first syringe from the compressed gas unit, operating the first syringe to transmit carbon dioxide from the first syringe to only the second syringe through the control valve assembly, adjusting the control valve assembly to communicably join the second syringe to the outlet conduit and to isolate the first syringe and the compressed gas unit from the second syringe, and operating the second syringe to transmit carbon dioxide from the second syringe to only the patient through the outlet conduit.

Other objects and advantages of the present invention will become apparent from the following detailed description when viewed in conjunction with the accompanying drawings, which set forth certain embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side perspective and partly schematic view of a preferred compressed gas unit in accordance with this invention including compressed gas (CO₂) cylinders, a pressure adjustable regulator and a separate solenoid.

FIG. 2 is a schematic front view of an alternative compressed gas unit enclosed in a housing.

FIG. 3 depicts a schematic layout of the components of the compressed gas unit of FIG. 2.

FIG. 4 is a somewhat simplified plan and partly schematic view of the system for controlled delivery of medical fluids in accordance with this invention.

FIG. 5 is a view similar to FIG. 4 wherein the control valve assembly is enlarged for clarity and the internal construction of the valve assembly is illustrated.

FIG. 6 is a simplified, schematic view of the outlet conduit and an alternative downstream fitting that may be used to interconnect the outlet conduit to the patient catheter.

FIG. 7 is a view similar to that of FIGS. 4-6 which depicts a medication administering syringe being attached to the downstream fitting by means of a connecting tube.

FIG. 8 is a perspective view of a control valve assembly featuring a dual handle for operating the stopcock and indicating which pair of flow passageways are open.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The detailed embodiments of the present invention are disclosed herein. It should be understood, however, that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, the details disclosed herein are not to be interpreted as limiting, but merely as a basis for teaching one skilled in the art how to make and/or use the invention.

The present invention provides a delivery system 10 for the effective, reliable and foolproof delivery of controlled amounts of a medical fluid such as CO₂, or other contrast media to a patient. In accordance with the present invention, delivery is achieved through the utilization of an integrated compressed gas unit 1 and a multi-part valve delivery system 14. The multi-part valve delivery system 14 delivers the fluid in precisely controlled amounts sequentially through a series of syringes such that it is impossible to directly connect the fluid source to the patient. At the same time, the delivery system 10 does not have to be disconnected and reconnected during the administration of medical fluid. This greatly reduces the intrusion of air into the system and the fluid being administered.

The present invention is intended to provide a portable, safe, reliable, and convenient source of medical gas such as CO₂ to health care professionals in hospital or medical office settings where a small volume of CO₂ or other gases is needed. The present invention is simple to manufacture and use because it does not require large regulators, an external power source, cumbersome large tanks or impellers for dispensing medical grade CO₂. The present invention utilizes a source of compressed gas to produce the desired pressure and airflow for the effective transformation of medical CO₂ liquid to medical grade CO₂ gas.

The present invention also provides for a compressed gas unit for delivering medical grade gas such as CO₂. In a preferred embodiment the compressed gas unit includes a portable compressed gas unit having at least one cylinder containing a compressed medical gas. A solenoid valve is communicably connected to the cylinder. There is a separate pressure adjustable gas regulator for selectively adjusting the pressure of the compressed gas provided from the cylinder to the solenoid. A source of electrical power is connected to the solenoid and an electronic switch is interconnected between the source of electrical power and the solenoid. The switch is adapted to be manually activated by a selected amount of voluntary fingertip pressure for selectively opening the solenoid to transmit pressure adjusted gas therethrough. A conduit is communicably attached to an outlet of the solenoid for delivering the transmitted gas to a destination where the gas may be used in a medical procedure or stored for later use.

The compressed gas may be any gas suitable for medical applications. Suitable compressed gases may include carbon dioxide, atmospheric air, nitrogen, helium and/or mixtures thereof. The compressed gas is contained in one or more compressed gas containers such as cylindrical cartridges. The electrical power source may be delivered by batteries providing between about 3-24 volts. Preferably, the electronic switch activates the solenoid when the switch is selectively depressed by fingertip pressure.

The conduit may include a hose and the destination may include a gas storage container. The container may include a reservoir bag or other reservoir or receptacle.

The system of this invention is particularly beneficial for delivering CO₂ for medical use. In medical uses, CO₂ is used because it is safer and has fewer complications than air or oxygen in the same uses. CO₂ diffuses more naturally in body tissue and is absorbed in the body more rapidly with fewer side effects. CO₂ used in decompartmentalization of tissues, arteries, veins and nerves and for radiological imaging, cardiac imaging, evaluation of vascularity of the heart and surrounding tissues, oncology and urology diagnostics. It is specifically used for imaging by infiltrating the tissues, body cavities and abdomen for better visualization. The CO₂ can also expand internal body cavities and tissues thereby enabling better diagnostic techniques.

The pressure adjusted CO₂ gas provided by the compressed gas unit of this invention is ultimately delivered to a flow control system. As will be explained below in greater detail, the flow control system provides a foolproof mechanism for the delivery of CO₂ to be used as needed by various medical devices for applications such as imaging, differentiation of tissues, arterial/venus/neurological separation, and treatment of stretch marks, facial wrinkles and dark circles. The separate pressure regulator interconnected between the gas container and the solenoid allows the pressure of the CO₂ or other gas to be controlled from about 0 psi to 120 psi. This allows the gas to be used for a variety of medical applications. In addition, and as will be appreciated based upon the following disclosure, the CO₂ may be delivered to a control valve assembly for the controlled delivery of the CO₂.

The system is portable, compact, and electronic so that it is convenient to utilize in the field for portable medical uses, military field uses and any other use requiring CO₂ or other medical gas for its performance. The system is safer than existing tank systems because it eliminates the risk of seal, valve or part malfunction, the potential for a disastrous explosion and the unwanted production of projectiles in a medical setting. It also eliminates the rust, dirt, bacteria and contaminants that can be present in refillable tanks. The system requires very little space to store and is much easier to use with a simple push button actuator to initiate operation using fingertip pressure. The system of the invention is much less expensive than current tank systems. In addition, the system utilizes compact compressed gas cartridges which can be delivered and transported in a small box. The compressed gas cartridges do not have to be transported to a filling station and do not present a risk of explosion in the event of a motor vehicle accident.

Referring now to FIG. 1, the compressed gas unit 1 of the present invention is disclosed. The compressed gas unit includes a solenoid 55 with at least one compressed gas (CO₂) cylinder 27 connected communicably to the solenoid 55. The compressed gas cylinder 27 is secured into position to the compressed gas unit 1 by means of cylinder cartridge puncture valve 26 and a fitting 74. In a preferred embodiment, the cylinder cartridge puncture valve 26 has a mechanism for piercing the cylinder 27, as is known in the art, and for holding or securing the cylinder 27 in place. Compressed air is delivered to the solenoid 55 from the compressed gas cylinder 27 through the cylinder cartridge puncture valve 26 and the conduit 73 of the fitting 74. The conduit 73 of the fitting 74 communicates with a threaded conduit 38 described more fully below.

The compressed gas unit 1 has at least one battery 65 held in place by a battery holder 42, for providing electrical power by which the solenoid 55 may be selectively activated and opened by a pressure activation switch or activation switch 37. The activation switch 37 is designed so that the solenoid 55 is opened when a physician or other medical personnel engages the activation switch 37 by voluntarily applying a small predetermined amount of fingertip pressure to the activation switch 37. It is not activated by a breathing sensor or other actuators designed to be operated by involuntary movement of the user's body. The battery 65 supplies power to the solenoid 55 through a switch wire assembly 23, which is connected to the activation switch 37. The activation switch 37 is mounted to a pressure nut 32 carried on threaded conduit 38. The compressed gas unit 1 has electrical wiring 39 for providing necessary electricity from the activation switch 37 to the solenoid 55.

The compressed gas unit 1 also comprises a separate black rock regulator 140, which is distinct from the solenoid 55. The black rock regulator 140 is controlled or adjusted by a regulator adjustment knob 30 to provide a selected level of pressure to the gas provided to the solenoid 55. The black rock regulator 140 is communicably connected to the compressed gas unit 1 by an elbow pipe 40. The elbow pipe 40 includes a threaded vertical conduit segment 41 joined to the black rock regulator 140 through a connector nut and the threaded horizontal conduit 38, which is engaged by pressure nut 32.

As discussed above, the compressed gas cylinder 27 is secured to the compressed gas unit 1 by the cartridge puncture valve 26 as is commonly known. In one embodiment, the compressed gas cylinder 27 is a 25 gram cylinder. Alternative capacities (e.g. 16, 36, 45 grams) may be used within the scope of this invention. Compressed air leaves the black rock regulator 140 at the regulator adjusted pressure through a 10/32″ hose port 12 b and flows through a hose junction 22, by means of a ⅛″ pressure hose 54, until reaching the 10/32″ hose port 12 affixed to the solenoid 55. From the hose port 12, the compressed air enters the solenoid 55. The compressed air unit 1 also has an outlet air port 25, which is connected to the solenoid 55 through intermediate 10/32″ hose port 12 a for transporting compressed gas, namely CO₂ from the solenoid 55 in the compressed gas unit 1 to the flow control system when the solenoid 55 is opened. Outlet gas may be monitored with a pressure gauge 52 connected to the hose junction 22 through a conduit 45 having threads 46. The threaded end of the conduit 45 interengages a nut 48 carried by the hose junction 22.

In certain embodiments a second compressed gas cylinder or cartridge 28, featuring a 16 g or 25 g compressed gas cylinder, may be used in addition to or in lieu of the primary gas cylinder 27. In still other embodiments, a larger compressed gas cylinder and expansion chamber may be substituted for the gas cartridges previously described in accordance with the invention. The size and number of compressed gas containers are not limitations of the invention.

FIGS. 2 and 3 depict an alternative embodiment of a compressed gas unit la wherein venous components of the gas unit la are enclosed in a housing 75 a. The components of the compressed gas unit la are designated by reference numerals that correspond to those of the previously described embodiment and further include lower case “a” designations. In particular, a CO₂ cartridge 27 a is connected by a puncture valve 26 a to a regulator 140 a. The regulator is controlled by an adjustment knob 30 a. The regulator 140 a is connected through a conduit 54 a to both a pressure gauge 52 a and a solenoid 55 a. More particularly, the pressure gauge 52 a is connected to a coupling 48 a. The solenoid 55 a is powered by a battery 65 a, which is itself held in place within the housing by a holder 42 a. A user accessible Luer fitting 25 a is communicably connected to the solenoid 55 a and extends exteriorly of the housing 75 a.

The compressed gas unit 1 a is activated to selectively open the solenoid 55 a by manually engaging the switch 37 a through voluntary fingertip pressure. This transmits the pressure regulated CO₂ or other gas through the solenoid 55 a and the fitting 25 a. The compressed gas unit la thereby operates in a manner analogous to that previously described to provide pressure adjusted CO₂ from the cartridge 27 a through the Luer fitting 25 a to the flow control system or other destination for the medical gas. The following are preferred examples of such applications.

The delivery of CO₂ as described above is further enhanced by the provision of a flow control system 1010 as disclosed with reference to FIGS. 4 to 8.

The present flow control system 1010 results from a realization that an improved, foolproof mechanism for safely delivering controlled amounts of a medical fluid such as CO₂ or other contrast media to a patient may be accomplished by utilizing a multi-part valve that delivers the fluid in precisely controlled amounts sequentially through a series of syringes such that it is impossible to directly connect the fluid source to the patient. At the same time, the delivery system does not have to be disconnected and reconnected during the administration of medical fluid. This greatly reduces the intrusion of air into the system and the fluid being administered.

The flow control system 1010 provides for controlled delivery of a medical fluid from a source of such fluid to a patient. As will be explained below in greater detail, the flow control system 1010 includes an inlet conduit that is communicably joined to a source of the medical fluid via the compressed gas unit and an outlet conduit that is communicably joined to the patient. First and second syringes are intermediate the inlet and outlet conduits. A control valve assembly interconnects the inlet and outlet conduits as well as the intermediate first and second syringes. The control valve assembly is alternatable between first, second, and third states. In the first state, the inlet communicates with the first syringe for transmitting fluid from the source to the first syringe. In the second state, the first syringe communicates with the second syringe and is isolated from the inlet and the outlet conduits for transmitting fluid from the first syringe to the second syringe. In the third state, the second syringe communicates with the outlet conduit and is isolated from the inlet conduit and the first syringe. This allows fluid to be transmitted from the second syringe to the patient through the outlet conduit.

In one embodiment, the control valve assembly includes a valve body having aligned inlet and outlet passageways that are communicably connectable to the inlet and outlet conduits respectively. The valve body further includes a pair of first and second transverse passageways that extend axially transversely to the inlet and outlet passageways and transversely to each other. A stopcock is mounted rotatably within the valve body and includes an angled channel having a pair of communicably interconnected channel segments that extend axially at an acute angle to one another. The channel segments of the stopcock are interconnected at an angle that is generally equivalent to the angle formed between each adjacent pair of non-aligned passageways in the valve body such that the stopcock is rotatable to align the channel segments with a selected adjacent pair of the non-aligned passageways to permit fluid communication between those passageways. Each of the transverse passageways is connectable to a respective syringe. The stopcock is selectively adjusted between first, second and third positions. In the first position, the channel segments communicably interconnect the inlet passageway and a first one of the transverse passageways. Fluid introduced through the inlet conduit portion is thereby transmitted through the inlet passageway and the channel of the stopcock to the first transverse passageway. This passageway directs the fluid to a first syringe attached thereto. In the second valve position, the stopcock aligns the channel segments with the first and second transverse passageways respectively. This isolates the fluid in the first syringe from both the inlet and outlet conduits. The first syringe is operated to direct the fluid through the first transverse passageway, the stopcock channel and the second transverse passageway into a second syringe joined to the second transverse passageway. In the third valve position, the stopcock is rotated to align the channel segments with the second transverse passageway and the outlet passageway respectively. This isolates the fluid in the second syringe from the fluid source, the inlet passageway and the first transverse passageway. The second syringe is then operated to drive the fluid through the second transverse passageway, the channel of the stopcock and the outlet passageway to the outlet conduit. The outlet conduit directs this fluid to the patient.

The respective longitudinal axes of the inlet and outlet passageways are aligned. The first and second transverse passageways may include respective longitudinal axes that form an angle of substantially 60 degrees with one another. The first transverse passageway may form an axial angle of substantially 60 degrees with the longitudinal axis of the inlet passageway and, similarly, the axis of the second transverse passageway may form an angle of substantially 60 degrees with the longitudinal axis of the outlet passageway.

The angular channel formed in the stopcock preferably features channel segments with respective longitudinal axes that form an angle of substantially 60 degrees. As used herein, “substantially 60 degrees” means that the angles are either precisely or approximately 60 degrees such that the channel segments of the stopcock are communicably and selectively interengagable with a respective pair of adjoining, non-aligned passageways in each of the three valve positions. Alternative angles may be featured when the inlet and outlet conduits are not aligned. A lever is attached to the valve body for adjusting the stopcock between the three alternate valve positions.

The inlet conduit may include a fitting for sealably interconnecting to a source of medical fluid. The fitting may include a one-way valve for limiting the flow of fluid to a single direction from the source of fluid to the valve assembly and for preventing flow in the opposite direction. The inlet conduit may include coiled tubing. A second one-way valve may be mounted within the inlet passageway of the valve body for restricting fluid flow from the valve body to the inlet conduit.

The valve assembly may further include a one-way outlet valve mounted in the outlet passageway for restricting fluid to flow to a single direction from the outlet passageway to the outlet conduit and for preventing fluid flow in the opposite direction. A second coil section of tubing is formed in the outlet conduit.

The outlet conduit may carry a downstream valve for bleeding and/or purging fluid and/or for administering an additive fluid to the controlled fluid. The outlet conduit may be communicably connected to a patient catheter. An additional one-way valve may be carried by the downstream valve to restrict flow of the fluid through the downstream valve to a single direction from the outlet conduit to the patient catheter.

The outlet conduit may alternatively be connected to a downstream fitting having a one-way valve for directing fluid flow from the outlet conduit through the fitting to the patient. The fitting may include a port that allows fluid to be purged or flushed from the catheter. The port may also be used to deliver medications through the fitting and the catheter to the patient. The downstream fitting may be connected to a medication or fluid administering syringe through a conduit that is attached to the downstream fitting. Respective Luer fittings may be used to interconnect the inlet and outlet conduits to the control valve. A Luer fitting may also be employed to connect the downstream valve or fitting to the catheter.

The system of this invention may alternatively feature sequential, multiple stage delivery of a medical fluid from a source to a patient through a pair of directional or multidirectional valves. A first such valve is operated to either deliver fluid from the source to a first syringe or to deliver fluid from the first syringe to the inlet of a second valve. The second valve is then operated to selectively deliver fluid from the first syringe through the second valve to a second syringe. Alternatively, the second valve may be operated to deliver the fluid from the second syringe to the downstream catheter or patient. A critical feature of this invention is that a precise volume or dosage of CO₂ or other medical liquid/gas is delivered sequentially in three distinct stages from the source to the patient. In each stage, the source, which is typically under pressure, remains totally isolated from the patient so that fluid is administered much more safely than in prior systems.

This invention further features a process for delivering medical fluid from a source of such fluid to a patient in controlled doses. The process involves providing inlet and outlet conduits that are connected respectively to a source of medical fluid and a patient. A control valve assembly and a pair of first and second syringes are interconnected between the inlet and outlet conduits. The control valve assembly is first operated to communicably join the fluid source and the first syringe and medical fluid is transmitted from the source to the first syringe. The control valve assembly is then adjusted to communicably join the first and second syringes while isolating the first syringe and the second syringe from the source of fluid. The first syringe is then operated to transmit medical fluid from the first syringe to the second syringe through the control valve assembly. The second syringe and the outlet conduit are then communicably joined by further adjusting the control valve assembly and the second syringe is operated to transmit medical fluid from the second syringe to the patient through the outlet conduit. The first syringe and the fluid source remain isolated from the second syringe.

There is shown in FIGS. 4 and 5 the flow control system 1010 for delivering controlled dosages of a medical contrast fluid such as carbon dioxide (CO₂) for use in the radiological imaging of arteries and veins of a patient's vascular system. Although this is a preferred application for the flow control system 1010, it should be understood that the flow control system 1010 may be used for the controlled delivery of various other types of liquids and gases administered as part of assorted surgical and medical procedures. As used herein, the term “fluid” should be understood to include various types of medical liquids and gases. By the same token, when “gas” is used herein, it should be understood that such description is likewise applicable to various types of medical liquids.

The flow control system 1010 includes an inlet conduit 1012 and an outlet conduit 1014 interconnected by a three-stage K-valve shaped control valve assembly 1016. The inlet conduit 1012 communicably interconnects a source of carbon dioxide from the compressed gas unit 1 with the control valve assembly 1016. The outlet conduit 1014 likewise communicably interconnects a discharge end of the control valve assembly 1016 with a catheter 1018 that is, in turn, operably connected to a patient, not shown.

The inlet conduit 1012 includes a Luer fitting 1020 having a G-tube seal 1022, which is selectively attached to the source of medical fluid, such as the CO₂ source. It should be understood that flow control system 1010 may be used with various sources of carbon dioxide including, but not limited to, pressurized tanks, bags and the CO₂mmander® manufactured by PMDA, LLC of North Fort Myers, Fla., which is described above with reference to FIGS. 1 to 3. A one-way directional valve 1024 with a Luer fitting 1026 is communicably joined to the fitting 1020. The Luer fitting 1026 is, in turn, communicably joined to a coiled medical tube 1028 having a length of approximately 18″. Various alternative lengths may be employed within the scope of this invention. The distal end of the tube 1028 carries a Luer fitting 1030.

The three-stage control valve assembly 1016 includes a generally K-shaped valve body 1032, which is preferably composed of various medical grade plastics, metals and/or metal alloys. Typically, the valve body 1032 includes a molded or otherwise unitary construction. More particularly, the valve body 1032 includes aligned intake and discharge branches 1034 and 1036, respectively, which, as best shown in FIG. 5, include respective aligned internal passageways 1038 and 1040. The valve body 1032 also includes first and second transverse valve legs 1042, 1044. Each valve leg 1042, 1044 extends at an angle of substantially 60 degrees from aligned branches 1034, 1036 of the valve body 1032. The first leg 1042 includes an interior passageway 1046 and the second valve leg 1044 includes an interior passageway 1048, which extend axially longitudinally through the respective first and second valve legs 1042, 1044. The passageways 1046, 1048 form angles of substantially 60 degrees apiece with the respective axial passageways 1038, 1040 of the aligned branches 1034, 1036.

The transverse first and second valve legs 1042, 1044 also extend at an angle of substantially degrees to one another. By the same token, the longitudinal axes of the passageways 1046, 1048 form an angle of substantially 60 degrees.

The control valve assembly 1016 further includes a stopcock 1059 that, best shown in FIG. 5, which is rotatably mounted within valve body 1032. The stopcock 1059 includes an angled stopcock channel 1061 comprising communicably interconnected channel segments 1063 and 1065 having respective longitudinal axes that extend at an angle of approximately 60 degrees to one another. As used herein, “approximately 60 degrees” should be understood to mean that the angle formed between the respective longitudinal axes of the channel segments 1063, 1065 is substantially equivalent to the angle formed between the longitudinal axes of respective pairs of the non-aligned adjacent passageways of valve body 1032 (e.g. respective pairs of passageways 1038, 1046; 1046, 1048; and 1048, 1040). This enables the channel segments to be communicably aligned with a selected pair of the passageways in the manner described more fully below. It should be understood that in alternative embodiments the passageways and channel segments may have other corresponding angles. This is particularly applicable when the intake and discharge passageways and/or the inlet and outlet conduits are not aligned.

As shown in FIG. 4, a valve lever 1067 is mounted to the valve body 1032 for selectively rotating the stopcock 1059 into a selected one of three positions. For example, in FIG. 5, the stopcock 1059 is positioned with channel segments 1063 and 1065 of angled stopcock channel 1061 communicably aligned with adjacent passageways 1038 and 1046 respectively. Alternately, and as described more fully below, the lever 1067 may be manipulated to align the channel segments 1063 and 1065 with respective passageways 1046 and 1048 as indicated by the channel shown in phantom in position 1061 b. The lever 1067 may be likewise operated to align the respective channel segments 1063 and 1065 with passageways 1048 and 1040 as indicated by the angled channel in position 1061 c. Such selective positioning of the stopcock 1059 provides for controlled multiple stage delivery of fluid through the control valve assembly 1016 from the inlet conduit 1012 to the outlet conduit 1014. This operation is described more fully below.

The intake branch 1034 of the valve body 1032 carries a complementary fitting for communicably interconnecting to the Luer fitting 1030 carried at the distal end of the tubing 1028. By the same token, the discharge branch 1036 of the valve body 1032 carries a complementary fitting for operably and communicably interconnecting with a Luer fitting 1050 carried at the proximal end of the outlet conduit 1014. The remaining elements of the discharge conduit are described more fully below. Aligned passageways 1038 and 1040 of the valve body 1032 include respective one-way valves 1052 and 1054, FIG. 5, which restrict or limit the flow of fluid within the respective passageways 1038 and 1040 to the direction indicated by arrows 1056 and 1058.

As further illustrated in FIGS. 4 and 5, the outlet conduit 1014 features a coiled medical tube 1060 that is communicably interconnected between the Luer fitting 1050 attached to the discharge branch 1036 of the valve body 1032 and a second Luer fitting 1062, which is communicably joined to a downstream valve 1064. The downstream valve 1064 includes a one-way valve 1066 that restricts fluid flow from the outlet conduit 1014 through the valve 1064 to the direction indicated by arrow 1068. The valve 1064 features a G-tube seal 1073 that prevents air from intruding into the system prior to connection of the valve 1064. The valve 1064 also includes a stopcock 1070 that is rotatably operated within the valve 1064 to selectively bleed or purge fluid from the flow control system 1010 through a port 1072. Exit port 1074 is selectively joined to patient catheter 1018. Various alternative two and three port stopcocks may be used in the downstream valve.

A reservoir syringe 1080 is communicably connected to axial passageway 1046 of the first valve leg 1042. Such interconnection is accomplished by a conventional Luer fitting 1082, the details of which will be known to persons skilled in the art. Similarly, a second, draw-push syringe 1084 is releasably attached by a Luer fitting 1086 to the distal end of the second valve leg 1044. This allows the second syringe 1084 to be communicably interconnected with the passageway 1048 through the second transverse valve leg 1044. The first and second syringes 1080 and 1084 are constructed and operated in a manner that will be known to persons skilled in the art.

The flow control system 1010 is operated to deliver CO₂ or other medical fluid to a patient in a controlled and extremely safe and reliable manner. This operation is performed as follows.

The inlet conduit 1012 is first interconnected between a source of carbon dioxide via the compressed gas unit 1 and the intake branch 1034 of the valve body 1032. The outlet conduit 1014 likewise is communicably interconnected between the discharge branch 1036 of the valve body 1032 and the downstream valve 1064, which is itself attached to the patient catheter 1018. The first and second syringes 1080 and 1084 are joined to the first and second valve legs 1042 and 1044 such that the first and second syringes communicate with the respective passageways 1046 and 1048. The syringes should be selected such that they have a size that accommodates a desired volume of gas to be administered to the patient during the radiological imaging or other medical/surgical procedure.

After multistage K-valve control assembly 1016 has been interconnected between the inlet and outlet conduit 1012 and 1014, and following attachment of the syringes 1080 and 1084 to the respective valve legs 1042 and 1044, the stopcock 1059 is operated by the valve lever 1067 to align the legs, or channel segments, 1063 and 1065 of the stopcock channel 1061 with the valve passageways 1038 and 1046 respectively. See FIG. 5. The source of CO₂ is then opened or otherwise operated as required to deliver gas through the inlet conduit 1012 to the control valve assembly 1016. More particularly, the gas is delivered through the one-way valve 1024 and the tubing 1028 to the inlet passageway 1038. The one-way valve 1052 prevents backflow of gas into the coil tubing 1028. The CO₂ proceeds in the direction indicated by arrow 1056 and is transmitted through the angled stopcock channel 1061 into the passageway 1046 of the first valve leg 1042. From there, the gas proceeds as indicated by arrow 1090 through the fitting 1082 and into the reservoir first syringe 1080. The CO₂ is introduced into the reservoir first syringe 1080 in this manner until it fills the syringe.

When the reservoir first syringe 1080 is filled, the operator manipulates lever 1067, FIG. 4, and rotates the control valve into the second stopcock channel position represented in phantom by 1061 b in FIG. 5. In that position, the channel segment 1063 is communicably aligned with the passageway 1046 and the channel segment 1065 is communicably aligned with the passageway 1048. The plunger 1081 of the reservoir first syringe 1080 is pushed and the gas previously deposited into the reservoir first syringe 1080 is transmitted through the passageway 1046 and the angled stopcock channel 1061 into the passageway 1048. From there, the gas is introduced into draw-push syringe 1084 as indicated by arrow 1092. As this operation occurs, only the transverse passageways and their attached syringes are communicably connected. Both syringes 1080, 1084 remain completely isolated from both the inlet passageway 1038 and the discharge passageway 1040. By the same token, the source of carbon dioxide and communicably joined intake passageway 1038 are isolated from the discharge passageway 1040 and the outlet conduit 1014 connected to the catheter 1018. The patient is thereby safely protected against being inadvertently administered a dangerous dosage of carbon dioxide directly from the source.

After the gas is transferred from the reservoir first syringe 1080 to the push-draw second syringe 1084, the operator manipulates the valve lever 1067 to rotate the stopcock 1059 to the third position, which is represented by the stopcock channel in position 1061 c. Therein, the channel segment 1063 is communicably aligned with the passageway 1048 and the channel segment 1065 is similarly aligned with the passageway 1040. To administer the CO₂in the second syringe 1084 to the patient, the plunger 1083 of the second syringe 1084 is depressed in the direction of arrow 1096. Gas is thereby delivered through the passageway 1048 and the stopcock channel into the passageway 1040. From there, the gas passes in the direction indicated by arrow 1058 through one-way valve 1054 and into tubing 1060. CO₂ is thereby transmitted in the direction indicated by arrow 1058 through the one-way valve 1054 and into the tubing 1060 of the outlet conduit 1014. The one-way valve 1054 prevents backflow of gas into the K-control valve assembly 1016.

The lever 1067 may be configured as an arrow or otherwise marked to include an arrow that points in the direction of the intended fluid flow. With the lever pointing toward the reservoir first syringe 1080, as shown in FIG. 4, the angled stopcock channel 1061 is in the position shown in FIG. 5 and fluid flow is directed toward the reservoir first syringe 1080. Alternatively, the lever 1067 may be rotated to point toward the second syringe 1084. In this position, the channel is in the position 1061 b shown in FIG. 5 and CO₂ is directed from the first syringe 1080 to the second syringe 1084. Finally, in the third stage of the process, the lever 1067 may be directed to point toward the discharge end of the passageway 1040 and the attached outlet conduit 1014. In this stage, angled channel 1061 is directed to the position 1061 c, shown in FIG. 5, such that fluid flow is directed from second syringe 1084 to the outlet conduit 1014.

CO₂ is delivered through the tube 1060 and into the downstream valve 1064. Once again, a one-way valve 1066 prevents the backflow of gas into the tubing. The stopcock 1070 is operated, as required, to either direct the CO₂ to the catheter 1018 and thereby to the patient, or to purge the gas through port 1072. The G-tube seal 1073 prevents air from entering the line.

Accordingly, the flow control system 1010 enables controlled amounts of CO₂ to be delivered to the patient in a safe and reliable manner. After the components are connected, they may remain connected during the entire medical procedure and do not then have to be disconnected and reconnected. This minimizes the possibility that air will intrude into the system and endanger the patient. Controlled and precise dosages of CO₂ are delivered, by the simple and foolproof operation of the control valve assembly 1016, from the reservoir first syringe 1080 to the push-draw second syringe 1084 and then to the patient. At each stage of the process, the inlet and outlet ends of the valve remain totally isolated from one another so that the risk of administering an explosive and potential deadly dose of CO₂ is eliminated.

FIG. 6 illustrates the discharge branch 1036 of the control valve assembly 1016. A one-way valve 1054 is again installed in the passageway 1040 to prevent backflow of gas into the control valve assembly 1016. In this version, the tube 1060 is communicably connected between the discharge branch 1036 and a fitting 1100 that may be used selectively to perform various functions. In particular, the fitting 1100 includes a one-way valve 1102 that prevents backflow of gas into the tube 1060. The fitting 1100 includes a Luer fitting 1104 that allows the fitting 1100 to be releasably attached to the catheter 1018. A flush port 1106 is communicably joined with the fitting 1100 and features a G-valve seal 1108 that permits a syringe (not shown) to be interconnected to the port 1106. This syringe may be used to administer medications through the fitting 1100 to the attached catheter 1018. As a result, such medications may be administered to the patient without having to disconnect the individual components of the fluid delivery system. This saves valuable time in a surgical or medical environment and reduces the risk that air will be introduced into the system. A syringe may also be attached to port 1106 to purge or flush the catheter as needed or desired.

FIG. 7 depicts still another embodiment of this invention wherein the medical tube 1060 is communicably interconnected between the discharge branch 1036 of the control valve assembly 1016 and a fitting 1100 a. The downstream fitting again includes a one-way valve 1102 a for preventing the backflow of gas or medication into the tube 1060. A Luer fitting 1104 a releasably interconnects the fitting 1100 a to the catheter 1018. An inlet/discharge port 1108 a is formed in the fitting 1100 a for selectively introducing medication into the patient catheter through the fitting 1100 a or alternatively purging or flushing the catheter as required. A line 1110 is communicably connected to port 1108 a and carries at its opposite end a Luer fitting 1112 for releasably attaching the line to a syringe 1114. The syringe 1114 is attached to the line 1100 through the fitting 1112 in order to optionally deliver medication to the catheter 1018 through the fitting 1100 a in the direction indicated by arrow 1116. Alternatively, fluid may be purged or flushed in the direction of arrow 1121 from the catheter and/or from the system through the line 1110 by drawing the plunger 1120 of the syringe 1114 rearwardly in the directions indicated by arrow 1122.

In alternative versions of this invention, medical fluid may be transmitted from a source to a patient in multiple stages, as described above, but utilizing multiple valves joined to respective syringes. In particular, in a first stage operation, gas or other fluid under pressure is delivered from the source through a first directional valve to a reservoir syringe communicably connected to the first valve. The reservoir syringe is also connected through the first valve to a second valve which is, in turn, communicably joined to a second syringe. The first valve is operated so that the reservoir syringe remains isolated from the second valve as fluid is delivered from the source to the first syringe through the first valve. When a selected volume of fluid is accommodated by the first syringe, the first valve is operated to connect the first syringe with the second valve. The second valve itself is operated to communicably connect the first syringe to the second syringe while, at the same time, isolating the second syringe from the patient. The second syringe is a push-draw syringe. The first syringe is operated with the second valve in the foregoing position to transmit the fluid from the first syringe to the second syringe. During this stage of the operation, both syringes remain isolated from the source and the patient. As a result, even if fluid under pressure is “stacked” in the reservoir syringe, this pressure is not delivered to the patient. Rather, the desired volume of the fluid is delivered instead to the push-draw syringe. The second valve is then operated to communicably join the push-draw syringe to the patient and/or patient catheter. Once again, the patient and/or patient are totally isolated from the source of fluid under pressure. As a result, a safe and selected volume of fluid is delivered from the push-draw syringe to the patient.

Various valve configurations and types of directional valve may be employed to perform the multi-stage delivery described above. In all versions of this invention, it is important that fluid first be delivered from a fluid source to a first syringe and then delivered sequentially to a second syringe. Ultimately, the fluid in the second, push-draw syringe is delivered sequentially to the patient. During each stage of the process, the source of fluid remains isolated from the patient. Typically, only one stage of the system operates at any given time.

There is shown in FIG. 8 an alternative control valve assembly 1016 a, which again features a generally K-shaped valve body 1032 a composed of materials similar to those previously described. Aligned inlet and outlet conduit segments 1034 a and 1036 a, as well as transverse or angled conduit segments 1042 a and 1044 a are selectively interconnected to communicate and transmit fluid flow through respective pairs of the conduits by a rotatable stopcock valve analogous to that disclosed in the previous embodiment. In this version, the stopcock is rotated by a dual handle lever 1067 a, which includes elongate handles 1069 a and 1071 a. These handles 1069 a, 1071 a diverge from the hub of the stopcock lever at an angle of approximately 60 degrees, which matches the angle between each adjacent pair of fluid transmitting conduits 1034 a, 1042 a, 1044 a and 1036 a in the control valve assembly 1016 a. Each of the handles 1069 a and 1071 a is elongated and carries a respective directional arrow 1073 a that is printed, embossed or otherwise formed along the handle.

The valve lever 1067 a is turned to operate the stopcock such that a selected pair of adjoining conduits are communicably interconnected to permit fluid flow therethrough. In particular, the stopcock is constructed such that the handles 1069 a and 1071 a are aligned with and extend along respective conduits that are communicably connected by the stopcock. In other words, the valve lever 1067 is axially rotated until the handles 1069 a and 1071 a are aligned with adjoining conduits through which fluid flow is required. The angle between the handles 1069 a, 1071 a matches the angle between the adjoining conduits, e.g. 60 degrees. The level: 1067 a may therefore be rotated to align diverging handles 1069 a and 1071 a respectively with either conduits 1034 a and 1042 a, 1042 a and 1044 a, or 1044 a and 1036 a. In FIG. 8, the handles are aligned with conduits 1044 a and 1036 a, and arrows 1073 a point in a direction that is substantially aligned with those conduits. This indicates that the valve lever 1067 a is rotated and adjusted such that fluid is able to flow through the valve body 1032 a from the transverse conduit 1044 a to the outlet conduit 1036 a. The valve lever 1067 a is rotated to selectively align with the other pairs of conduits and thereby open the fluid flow passageway between the selected pair. The use of a dual handle valve lever 1067 a clarifies and facilitates usage of the control valve assembly. Otherwise, the valve lever employed in the version of FIG. 8 is constructed and operates analogously to the valve lever disclosed in FIGS. 4-6.

The use of multiple syringes is particularly critical and eliminates the risk of stacking that often occurs when a medical fluid is delivered under pressure directly from a source of fluid to a single delivery syringe. In that case, the syringe may be filled with fluid that exceeds the nominal volume of the syringe due to pressure stacking. If such fluid were to be delivered directly to the patient, this could result in a potentially dangerous overdose or fluid flooding. By transmitting the fluid from a reservoir syringe into a second, push-draw syringe, the pressure is equalized and only the fluid volume and pressure accommodated by the second syringe are delivered safely to the patient.

It is contemplated that the apparatus of the present invention be used in methods and procedures requiring delivery of medical gas. The following are examples of such applications:

CO₂ is useful in the following arterial procedures: abdominal aortography (aneurysm, stenosis) iliac arteriography (stenosis), runoff analysis of the lower extremities (stenosis, occlusion), renal arteriography (stenosis, arteriovenuous fistula [AVF], aneurysm, tumor), renal arterial transplantation (stenosis, bleeding, AVF), and visceral arteriography (anatomy, bleeding, AVF, tumor).

CO₂ is useful in the following venous procedures: venography of the upper extremities (stenosis, thrombosis), inferior vena cavography (prior to filter insertion), wedged hepatic venography (visualization of portal vein), direct portography (anatomy, varices), and splenoportograpy (visualization of portal vein).

CO₂ is likewise useful in the following interventional procedures: balloon angioplasty (arterial venous), stent placement (arterial, venous), embolization (renal, hepatic, pelvic, mesenteric) transjugular intrahepatic portacaval shunt creation, and transcatheter biopsy (hepatic, renal).

Angiography is performed by injecting microbubbles of CO₂ through a catheter placed in the hepatic artery following conventional hepatic angiography. Vascular findings on US angiography can be classified into four patterns depending on the tumor vascularity relative to the surrounding liver parenchyma: hypervascular, isovascular, hypovascular, and a vascular spot in a hypovascular background.

Improved CT colonography, an accurate screening tool for colorectal cancer, is performed using a small flexible rectal catheter with automated CO₂ delivery. This accomplishes improved distention with less post-procedural discomfort.

Carbon dioxide (CO₂) gas is used as an alternative contrast to iodinated contrast material. The gas produces negative contrast because of its low atomic number and its low density compared with the surrounding tissues. When injected into a blood vessel, carbon dioxide bubbles displace blood, allowing vascular imaging. Because of the low density of the gas, a digital substraction angiographic technique is necessary for optimal imaging. The gas bubble can be visible on a standard radiograph and fluoroscopic image.

CO₂ insufflation for colonoscopy improves productivity of the endoscopy unit.

Endoscopic thyroid resection involves creating a working space within the neck using CO₂ insufflation devices, with both axillary and neck approaches as starting points for dissection.

CO₂ insufflators are used during laparoscopic surgery.

Because of the lack of nephrotoxicity and allergic reactions, CO₂ is increasingly used as a contrast agent for diagnostic angiography and vascular interventions in both the arterial and venous circulation.

CO₂ is particularly useful in patients with renal insufficiency or a history of hypersensitivity to iodinated contrast medium.

CO₂ is compressible during injection and extends in the vessel as it exits the catheter.

CO₂ is lighter than blood plasma; therefore, it floats above the blood. When injected into a large vessel such as the aorta or inferior vena cava, CO₂ bubbles flow along the anterior part of the vessel with incomplete blood displacement along the posterior portion.

CO₂ causes no allergic reaction. Because CO₂ is a natural byproduct, it has no likelihood of causing a hypersensitivity reaction. Therefore, the gas is an ideal alternative. Unlimited amounts of CO₂ can be used for vascular imaging because the gas is effectively eliminated by means of respiration.

CO₂ is partially useful in patients with compromised cardiac and renal function who are undergoing complex vascular interventions.

Intranasal carbon dioxide is very promising as a safe and effective treatment to provide rapid relief for seasonal allergic rhinitis.

CO₂ is used for transient respiratory stimulation; encouragement of deep breathing and coughing to prevent or treat aterectasis; to provide a close-to-physiological atmosphere (mixed with oxygen) for the operation of artificial organs such as the membrane dialyzer (kidney) and the pump oxygenator; and for injection into body cavities during surgical procedures.

Medical asepsis is accomplished by using CO₂ an implant devices prior to surgical implantation. CO₂ may be effectively delivered to a foam generating tip for creating a medical foam for use in wound care and hair loss treatment.

Additionally, the present invention is used in methods requiring the delivery of other gasses such as: Carbon Dioxide U.S.P., Medical Air U.S.P., Helium U.S.P., Nitrogen U.S.P., Nitrous Oxide U.S.P., Oxygen U.S.P. and any combination thereof.

In one embodiment, the present invention provides for an apparatus and use in a method whereby delivery of a gas alone is desired. The delivery of gas is independent of systems whereby a gas is delivered as a carrier for medications or other materials.

From the foregoing it may be seen that the apparatus of this invention provides for a system for safely delivering a controlled volume of a medical fluid to a patient and, more particularly to a system for delivery a controlled flow of carbon dioxide (CO₂) or other contrast media in order to obtain radiological images. While this detailed description has set forth particularly preferred embodiments of the apparatus of this invention, numerous modifications and variations of the structure of this invention, all within the scope of the invention, will readily occur to those skilled in the art. Accordingly, it is understood that this description is illustrative only of the principles of the invention and is not limitative thereof.

Although specific features of the invention are shown in some of the drawings and not others, this is for convenience only, as each feature may be combined with any and all of the other features in accordance with this invention.

While the invention has been described in its preferred form or embodiment with some degree of particularity, it is understood that this description has been given only by way of example, and that numerous changes in the details of construction, fabrication, and use, including the combination and arrangement of parts, may be made without departing from the spirit and scope of the invention. 

The invention claimed is:
 1. A method for using CO₂ as a contrast material in medical imaging procedures, comprising: providing a source of pressurized CO₂; connecting the source of pressurized CO₂ to a compressed gas unit for controlling delivery of the CO₂, wherein the source of pressurized CO₂ is a cartridge filled with compressed CO₂ and the compressed gas unit includes a pressure regulator outputting CO₂ at a selected level of pressure; regulating pressure of the CO₂ delivered by the compressed gas unit; transmitting the pressurized CO₂ from the compressed gas unit to a control valve assembly for delivery to a patient in controlled dosages, wherein the control valve assembly includes a valve body having aligned inlet and outlet ports that are respectively communicably connectable to inlet conduit and the outlet conduits; sequentially processing the CO₂ with the control valve assembly and delivering the CO₂ to the patient as a contrast media, wherein the step of sequentially processing includes providing the inlet and outlet conduits connected respectively to the compressed gas unit and the patient, providing the control valve assembly which is interconnected between the inlet and outlet conduits, operating the control valve assembly to communicably join the compressed gas unit and a syringe and transmitting CO₂ from the compressed gas unit to only the syringe, adjusting the control valve assembly to communicably join the syringe to the outlet conduit and to isolate the compressed gas unit from then syringe, and operating the syringe to transmit CO₂ from the syringe to only the patient through the outlet conduit. 